This invention relates to weld metal deposits suitable for forming hard facings on metallic articles such as, for example, work rolls or backup rolls for use in a rolling mill for metal.
It is well-known practice to use arc welding to provide various articles, including rolls for hot rolling mills, with a facing of a wear-resistant alloy. Below are listed some examples of weld metal compositions which have been used in facings on rolls for hot rolling mills:
______________________________________ Example No. 1 2 3 4 ______________________________________ C % 0.22 1.10 0.05 0.08 Si % 1.0 1.25 0.30 0.55 Mn % 0.5 1.10 1.50 1.30 Cr % 5.0 7.70 4.80 2.5 Mo % 11 1.00 0.63 1.0 V % 0.3 -- -- -- W % -- 1.60 -- -- Fe remainder remainder remainder remainder ______________________________________
The weld deposit of Example 2 has the best wear-resistance but also has a strong tendency to form hot cracks (solidification cracks) and therefore can in practice be used in such cases only when hot cracks in the weld deposit are allowable, for instance, in rollers for roller conveyors and other rollers subjected to comparatively low working pressures. Weld deposits according to Examples 1, 3 and 4, and similar alloys, are less subject to cracks and have been used in practice as a coating material for work rolls in hot rolling mills, that is, rolls required to perform a hot metal rolling operation. Economical considerations, however, frequently exclude the use of the known deposit alloys, the wear-resistance or useful life obtainable with the resulting facings proving insufficient to weigh up the cost of their use for the repair or the manufacture of rolls for hot rolling mills.
It is an object of the invention to provide an improved weld metal deposit particularly suited for hard facing purposes which has little or no tendency to cracking and has a satisfactory hardness combined with a high resistance to wear. A more particular object is the provision of a weld metal deposit of a composition particularly suited for the hard facing of hot working tools, that is, tools used for the working of metals at elevated temperatures, for instance, drop forging dies, pressing dies, extruding press nozzles, dies for die casting machines, mandrels for piercing mills, mandrels for the hot drawing of tubes and rolls for hot rolling mills.